Electric power transmission and distribution system



Sept. 19, 1939.. A 2,173,121

ELECTRIC POWER TRANSMISSION AND DISTRIBUTION SYSTEM Filed Nov. 24. 19372 Sheets-Sheet 1 Sept. "19, 1939. A. R. LOCKE 2,173,121

ELECTRIC POWER TRANSMISSION AND DISTRIBUTION SYSTEM I Filed Nov. 24,1937 2 Sheets-Sheet 2 P T T W W w w i @WELQ 33 g it Q Q g ME 2U flamzwe.

Patented Sept. 19, 1939 I UNITEDSTATES PATENT OFFICE ELECTRIC POWERTRANSMISSION AND DISTRIBUTION SYSTEM Albert R. Locke, Oak Park, Ill.

Application November 24, 1937, Serial No. 176,230

'14 Claims. (Cl. 171-97) This invention relates to an electric powertain other difliculties and has many disadvantransmission anddistribution system, and more tageous features. It is of course wellknown that particularly to a system in which electric energy with hightension alternating current transmisis. transmitted in the form ofuni-directional sion, it is possible to take small amounts of powercurrent. at high tension from the high tension line to Large quantitiesof electric power are now aloperate switching or auxiliary apparatus ofthe most universally transmitted over transmission high tension line, orfor branch lines connected lines as high tension, alternating current.As therewith, and to supply energy for measuring the demand for electricpower has increased and devices for ammeters and voltmeters that indi-ID as the distahce from the generating center over cate the condition ofthe high tension line. It which the power must be transmitted is inisalso possible with the transmission of power by creased, there has beena constant tendency to high tension alternating current to tap thetransincrease thevoltage of transmission in order to mission line andobtain small amounts of power minimize losses, and particularly the PRlosses. for lighting purposes, such for example, as street Increasingthe tension or voltage of an alternatlights for small communitiesthrough which the 15 ing current transmission line, however,introtransmission line passes. On the other hand, duces seriousdifliculties which restrict the diswhen high tension uni-directionalcurrent, which tance to which alternating current power can be issubstantially free from pulsation or ripple is transmitted economically.It has been found employed, it is impractical and inadvisable to thatthe charging current for instance, becomes draw small amounts of powerfrom the trans- 20 very great when the load at the remote end of thmission line since there is no convenient means transmission line hasbeen disconnected. Infor reducing the potential of the line,

deed, this loss by charging current is sometimes Under the existing hightension alternating as great as the load current itself. Theinsulacurrent transmission system, it is also common tion of the hightension line becomes a difiicult practice for several high tension linesto deliver 5 problem and the insulators are subject to failure powerinto a common low tension alternating due to-losses therein caused byalternating eleccurrent network, wherein the frequency of the triostresses to which they are subjected. .Cororia network is controlled byone or more of the gem is another serious trouble since corona dependscrating stations feeding the high tension line.

upon the peak voltage and not upon the mean This cannot bedone withhigh'tension direct cur- 30 effective voltage. As a remedy for these andrent transmission of the type referred to above, other troubles, it hasbeen proposed to generate since the frequency'of the high tensionalternatalternating current at high tension and to coning current at thegenerating station cannot convert the alternating current into directcurrent trol the frequency of the low tension alternating and transmitthe direct current at high tension current power consuming network overthe direct 35 over the high tension line, and use it at the concurrenttransmission line. suming end either as direct current at high ten- Itis an object of this invention to provide an sion or to convert it. intoalternating or direct electric power transmission and distributionsyscurrent at low tension and employ it as such. tern wherein theadvantages of v transmitting 40 In the past, it has generally beenconsidered power by direct current are realized and wherein 40' by powerplant engineers that it is necessary to many of the disadvantages suchas those enumtransmit a uni-directional current which aperated above,are obviated. proaches the uniformity of a direct current, gen- Inaccordance with this invention, polyphase erated. That is to say, it wasgenerally considalternating current is passed through a plurality eredto be desirable to eliminate as far as posof voltag step-uptransformers, and polyphase 45 sible any ripple or pulsation in theuni-direcpulsating uni-directional current is derived tional current. Tothis end, the alternating curtherefrom by means of a plurality ofsuitable recrent from which the uni-directional current is tifyingdevices. Each rectifying device is conderived has been supplied in alarge number of nected to a conducting path of a multi-conductor phases,which in some instances have even been transmission line, there being aplurality of.outgo as high as forty or fifty phases. going conductingpaths over which the pulsating While the transmission of high tensionuni-diuni-directional current passes in one direction rectional currentin this manner eliminates many and a corresponding plurality of returnconductof the troubles present with high tension altering paths overwhich the pulsating uni-direcin current r n mission, it introducescertional current passes in the opposite direction. 55

Thus, each out-going conducting path of the transmission line hasimpressed thereon a series of uni-directional pulsations, such forexample, as a series of rectified half-waves of different phasesequence. The half-waves or uni-directional pulsation of difierent phaseon each out going conducting path of the transmission line areselectively segregaated at the end of the transmission line and returnover different return conductor paths. This process of selectivesegregation is such that if a load were connected between any oneout-going path and any one returning path, only a half-wave oruni-directional pulsation of a single phase would be obtained. By virtueof this selective segregation of the unidirectional pulsations ofdifferent phase, it is possible to obtain either alternating orpulsating uni-directional current from the transmission line throughstep-down transformers. The alternating current derived from thetransmission line may be of the same phase as that at the power sourceor it may be any other phase, as desired.

In accordance with this invention, means is also provided which permitsa plurality of power sources to feed into a common distribution network.

It is thus an object of this invention to provide a novel transmissionand distribution systern having the above characteristics.

It is a further object of this invention to provide a novel transmissionsystem and novel means for transmitting and receiving power whichemploys polyphase pulsating unidirectional current.

Another object of this invention is to provide a novel method and meansof transmitting electric energy by means of uni-directional current,which is economical and which is rugged and reliable in use.

Another and further object of this invention is to provide a novel hightension uni-directional transmission system from which a low voltagealternating current may be obtained.

Another and still further object of this invention is to provide a novelmethod and means for deriving alternating current from a high tensionuni-directional transmission transmission system.

The novel feature which I believe to be characteristic of my inventionare set forth with particularity in the appended claims. My inventionitself, however, both as to its organization, manner of construction,and .methods of operation, together with further objects and advantagesthereof, may best be understood by reference to the followingdescription taken in connection with the accompanying drawings in which:

Figure 1 illustrates schematically a high tension uni-directionalcurrent transmission and distribution system wherein the source of poweris two phase alternating current and wherein the main load ordistribution system is three phase alternating current;' and Figure 2 isa schematic view illustrating a high tension uni-directional currenttransmission and distribution system, wherein the source of power isthree phase alternating current and wherein the main load ordistribution-network is also a three phase alternating current network.

In the power transmission and distribution system illustrated in Figure1, the source of electric power is illustrated as being a four wire, Twophase. alternating current line I II, and the main distribution networkII is illustrated as 3 three wire, three phase distribution network. Thevoltage of the twophase alternating current source is raised through aplurality of transformers I2, I3, I4 and I5 having their respectiveprimary windings I6, I I, I8 and I9 connected to one phase of line I8,and a plurality of transformers 28, 2|, 22 and 23 having their primarywindings 24, 25, 26 and 21 respectively connected to the other phase ofline H]. Transformers I2 to I5 and 20 to 23 are of the usual iron coretype commonly employed in power distribution systems. Each of.transformers I2 to I5 and 20 to 23 are provided with a pair of secondarywindings 28 to 43 respectively which are connected to the transmissionsystem in a novel manner presently to be described.

The transmission line which is to carry the power of the transmissionand distribution system of Figure 1 includes four out-going conductingpaths 44, 45, 46 and 41 and four return conducting paths 48, 49, 50 and5I. In other words, conductors 44 to 41 are designed to carryuni-directional current in one direction while conductors 48 to 5! aredesigned to carry unidirectional current in the opposite direction. Itwill, of course, be understood that the eight conductors 44 to SIinclusive provide the transmission line by which high tensionuni-directional current is transmitted over a relatively great distance.

In order to obtain high tension uni-directional voltage for transmissionover the transmission line, a plurality of rectifying devices 52, 53, 54and 55 are provided each having four anodes 55-5B-5'I58, 59- -586IB2,6364-6586, and 6'l686970, and each having a single cathode H, l2, l3,and I4 respectively. The lower ends of windings 28, 38, 30, 38, 32, 4D,34 and 42 are connected to anodes 58, 51, 82, BI, 55, 85, 10 and 69respectively of the rectifying de vices. The upper ends of winding 29,37, 3|, 39, 33, 4|, 35 and 43 are connected to anodes 56, 55, 80, 59,84, 83, 68 and 61 respectively of the rectifying devices. Cathodes II,12, I3 and '14 are connected to conductors 44, 45, 46 and 41respectively. Return conductor 48 is connected to the upper end ofwinding 28, the upper end of winding 38, the lower end of winding M, andthe lower end of winding 35. Return conductor 49 is connected to theupper end of winding 30, the upper end of winding 48, the lower end ofwinding 29, and the lower end of winding 43. Return conductor 58 isconnected to the upper end of winding 32, the upper end of winding 42,

- the lower end of winding 31 and the lower end of winding 3|. Returnconductor 5| is connected to the upper end of winding 36, the upper endof winding 34, the lower end of winding 39, and the lower end of winding33.

The transmission line comprising conductors 44 .to SI terminates in aplurality of transformers 15 to 82 inclusive. Transformer 15 has twoprimary windings 83 and 84 and a secondary winding. Similarly,transformer 16 is provided with two primary windings 86 and 81 and asecondary winding 88; transformer 11 is provided with two primarywindings 89 and 90 and a secondary winding 9|; transformer 18 isprovided with two primary windings 92 and Bland a secondary winding 94;transformer 19 is provided with two primary windings 95 and 98, and asecondary winding 91; transformer 80 is provided with two primarywindings 98 and 99 and a secondary winding I00; transformer 8| isprovided with two primary windings IM and H12,

and a secondary winding I03; and transformer 02 is provided with twoprimary windings I 04 and I05 and a secondary winding I00.

For a reason which will presently appear, a

similar number of rectifying devices I01, I00, I00,

and H0 are provided at the terminating end of the transmission line.Rectifying devices I01 to I I0 and rectifying devices 52 to 55 arepreferably of the mercury vapor electron discharge type and morecommonly known to the trade as "mercury vapor tub rectifier. RectifierI01 is provided with four anodes III, II2, III and H4 and one cathodeIIi. Rectifier I00 is provided with four anodes H6, H1, II8 and Ill andone cathode I20. Rectifier I0! is provided with four anodes I2I, I22,I22 and-I24 and one cathode I25. Rectifier ,I I0 is provided with fouranodes I20, I21, I20 and I29 and one cathode I30. Anodes III and H2 areconnected to the lower ends of windings 00 and 00 respectively, whileanodes II! and H4 are connected to the upper ends of windings 01 and 04respectively. Anodes H6 and H1 are connected to the lower ends ofwindings 09 and 02 respectively, while anodes III and II! are connectedto the upper ends of windings 03 and 00 respectively.

Anodes I2If and I22 are connected to the lower ends of windings 05 and.08 respectively, while anodes I23 and I24 are connected to the upperwave.

ends of windings 99 and 90 respectively. Anodes I26 .and I21 areconnected to the lower ends of windings IM and I04 respectively, whileanodes I28 and I29 are connected to the upper ends of windings I04 and'I0l respectively. Conductors 40, 49, 50 and SI are connected directly tocathodes II5, I20, I25 and I20 respectively.

As shown in the drawings, secondaries 05, 00, SI, 94, 91, I00, I00 andI06 are connected to the distribution line or network 1 in such a way asto supply three phase alternating current thereto.

From a close inspection of Figure 1 of the drawings, it will be foundthat the secondaries of the transformers which are connected to thesource I0, are connected to the rectifiers H, '12, 13 and 14 in such amanner that full wave rectification of the two phase alternating currentsupply is obtained. This is by virtue of the fact that two of the anodesof each rectifier are connected to a transformer which is connectedacross one phase 'of the source, while the other two anodes of therectifier are connected to a transformer which is connected across theother phase of the source. The double secondary windings of eachtransformer are connected to the rectifiers in the manner shown topermit full wave rectification; that is to say, the negative half ofeach alternating current wave is inverted to obtain a double positivehalf wave from the full alternating current Thus itwill be understoodthat four separate wave trains are travelling out over each out-goingconductor in different phase sequence with respect to each other. Inother words, on each out-going conductor 44, 45, 46 and 41 of thetransmission line there is the positive half wave and the invertednegative half wave of one phase and the positive half wave and theinverted nega-- line, and return over .diiferent return conductors-- tocomplete the circuit. Thus the half wave or uni-directional pulsationderived from secondary winding 20 and anode 58 passes through primarywinding 04, return conductor and then back to the opposite end ofwinding 20. The half wave The half wave derived from winding 28 passesout over out-going conductor 44 through primary winding I05 back overreturn conductor 5| to the opposite end of winding 30. The half wave oruni-directional pulsation derived from secondary winding 21 passes outover out-going conductor 44 through primary winding 08 and back overreturn conductor to the opposite end of control winding 21, thuscompleting the circuit. We thus see that while a portion of each of theclosed circuits over which the uni-directional pulsation of difierentphase sequence are passed from rectifier 1I, another portion is separateand distinct for each different train of uni-directional pulsations ofdifferent phase sequence.

In a similar manner the closed path over which the uni-directionalpulsation derived from secondary winding 24 passes includes out-goingcon-- ductor 45, primary winding 00 and return conductor 49. The closedcircuit of secondary windtional pulsation derived from the secondarywinding 32 passes, includes out-going conductor 46, primary winding 00and return conductor II. The closed circuit of secondary winding 33includes out-going conductor 48, primary winding IM and return conductor5|. The closed-circuit of secondary winding 40 includes out-goingconductor 46, primary winding 93 and return conductor 49. The closedcircuit of secondary winding 4I includes out-going conductor 46, primarywinding 06 and return conductor 40.

The closed circuit over which the uni-directional pulsation passes,which is derived from winding 24, includes out-going conductor 41,primary winding I02 and return conductor 5|. The

closed circuit of secondary winding 25 includes out-going conductor 41,primary winding I03 and return conductor 40. The'closed circuit ofsecondary winding 42 includes out-going conductor 41, primary winding 09and return conductor 50. The closed circuit of secondary winding 43includes out-going conductor 41, primary winding 92 and return conductor49.

From the above description of the various closed circuits over whichtheuni-directional pulsations of different phase sequence pass, it willreadily be appreciated that while-every out-going and return conductorcontain four sets of uni-directional pulsation of different phase, anyone outgoing conductor and any one return conductor onlydefines a closedpath for a uni-directional train of pulsations of one phase. It isentirely by virtue of this selective segregation of unidirectionalpulsation of different phase, that the beneficial results of thisinvention are obtained. Thus any particular wave train or series ofunidirectional pulsations may be obtaired by properly selecting anout-going conductor and a return conductor, and this wave train orseries of uni-directional pulsation may be caused to pass through awinding of a transformer in any desired direction. By combining oneseries of unidirectional pulsations of one phase with a different seriesof uni-directional pulsations of a different phase in two windings of atransformer either alternating current or uni-directional current may beobtained from the secondary of the transformer depending upon thedirection that the uni-directional pulsations are passed through theprimary windings of the transformer. Due to the fact that there are aplurality of trains of uni-directional pulsation passing over thetransmission line, it will also be apparent that polyphase alternatingcurrent may be obtained through suitable step-down transformers.

For the same reasons as pointed out above, it is possible to provideeither an alternating current or a uni-directional step-down tap-off ofthe main transmission'line anywhere along its length. Thus, at I3I Ihave illustrated a three phase takeoff from the main transmission line.purpose vtwo transformers I32 and I33 are employed having secondarywindings I34 and I35 respectively and primary windings I36 and I31respectively which are tapped at their midpoint. The left hand side ofprimary winding I36 is energized by uni-directional pulsations of onephase which are obtained by tapping out-going conductor 44 and returnconductor 50. The inverted half cycle complement, of the uni-directionalpulsations threading the left side of winding I32, is caused to passthrough the right side of winding I32 by tapping out-going conductor 44and return conductor 5| as shown in the drawings. Since theuni-directional pulsations pass from right to left in the left side ofwinding I36 and from left to right in the right side of winding I36, itis clear that a single phase alternating current is obtained in thesecondary winding I34 of transformer I32. Similarly a uni-directionalpulsation of one phase and the inverted half cycle complement thereof,are caused to pass through winding I31 by tapping out-going conductor 34and connecting it to the midpoint of winding I31 and connecting theopposite ends of winding I31 to return conductors 5| and 48.

Since all four of .the return conductors which have been tapped by theopposite ends of windings I36 and I31 are different, it is clear thatthe single phase alternating current obtained in the secondary windingI35 of transformer I32, is out of phase with respect to the single phasealternating current obtained in winding I34 of transformer I32. ofwinding I34 and the midpoint of winding I35, three phase alternatingcurrent is obtained on the three conductors leading from' the left sideof winding I34, the left side of winding I35 and I the right side ofwinding I35.

A direct current or uni-directional step-down tap-off from the maintransmission line is indicated generally at I35. This tap-off isobtained by employing an ordinary iron core transformer having fourprimary windings I39, I40, I and I42 and a single secondary winding I43.The four different trains of uni-directional pulsations of differentphase are caused to pass through windings I39, I40, I and I43 in thesame direction. It will thus be apparent that a uni-directionalpulsating current having a wave form which is the combination of fourhalf cycles 90 out of phase with respect to each other is obtained inthe secondary winding I 43. The uni- For this By connecting the rightend primary winding, any desired reduction in voltage may be obtained.

By way of further illustration, a plurality of additional take-offs areillustrated by conductors I44. Reading from left to right, the first twoconductors represent a half wave take-off from main conductors 41 and5|. the second pair represent a takeoff from main conductors 46 and 50,the third pair represent a take-off from main conductors 45 and 49, andthe fourth pair represent a take-off from main conductors 44 and 48.

These half wave take-off or uni-directional pulsations of differentphase sequence may be combined in any manner desired to obtain eithersingle phase or polyphase alternating current, or pulsatinguni-directional current.

By virtue of the fact that rectifying devices are provided at the headof each out-going conductor 44, 45, 46 and 41 and by virtue of the factthat rectifying devices are provided at the beginning of each returnconducting path 48, 49. 50 and 5|, it is clear that stray and parasiticcurrents are substantially eliminated from the transmission line.Furthermore, it will be understood by those skilled in the art that byvirtue of the arrangement set forth and described that more than onesource of electric energy may be connected to the distribution network1, this is primarily by virtue of the fact that the wave form of eachhalf cycle of alternating current is substantially identical with thewave form of the uni-directional pulsation traveling over thetransmission line.

It will also be understood by those skilled in the art that the powertransmission and distribution system described above is substantiallyselfequalizing. This is by reason of the fact that transformers 15 to 82inclusive, are all connected to a common bus I I which brings about anenergy feedback due to a potential difference whenever an excessive loadis placed on some one portion of the transmission line, such for exampleas might be placed on it by the application of a very heavy load at I3IThis is extraordinarily advantageous in a commercial installation, notonly because of its normal load equalizing effect, but also becauseeither a direct short circuit or an open circuit in some part ofthetransmission line will not prevent operation of the system, nor of thepower take-off network.

It will also be apparent to those skilled in the art, that this systemis peculiarly well suited for handling a fluctuating load. It is also tobe untem is illustrated schematically wherein the tor-and taken with anysource of electric energy is a four wire three phase power supply I58.The power is transmitted in a manner similar to that described inconnection with the description of Figure 1 over a twelve wiretransmission'line indicated generally as I5I. The distribution networkI52 is a four wire three phase distribution network.

Where a three phase alternating current source is employed to obtainpower for transmitting high tension unidirectional current over amulticonductor' transmission line, six rectifying devices of the mercuryvapor tube rectifier" type are preferably employed at the transmittingend and six similar rectiflers I59, I88, I8I, I82, I83 and I84 areemployed at the receiving end or the distribution end of thetransmission line. Each rectifier is provided with six anodes I85, I88,I81, I88, I89 and I18. Six three phase transformers I1I, I12, I13, I14,I15 and I18 are connected to the four wire three phase alternatingcurrent supply line I58. Each three phase transformer is provided withthree primary windings I11, I18 and I19 which are connected between theneutral wire and the respective phase wires of the three phasealternating current supply line I58. Each transformer is also providedwith six secondary windings I88 to I85 inclusive, one end of eachsecondary winding being connected to its associated rectifier in themanner shown in the drawings. The transmission line I5I comprises sixoutgoing conductors I88 to I9I inclusive which carry uni-directionalpulsations in one direction and six return conductors I92 to I91inclusive which carry uni-directional pulsations in the oppositedirection.

The receiving or distribution end of the transmission line I5 I hasconnectedthereto six three phase transformers I98 to 288 inclusive whichare similar in construction to transformers I1I to I18 inclusive. Eachof transformers I98 to 288 is provided with three secondary windings284, 285 and 288 and six primary windings 281, 288, 289, 2I8, 2H and2I2. The upper side of each winding 28,4, 285 and 288'is connected tothe grounded neutral of the four wire three phase alternatingcurrent'distribution system while the lower side of windings 284, 285and 288 are connected respectively to the other three wires ofthedistribution system.

It will readily be understood from the connections shown in the drawingsthat each rectifying device I58 to I58 inclusive impresses on itsoutgoing conductor I88 to I9I respectively, the conductors beingconnected to the cathode of each rectifying device, six trains ofuni-directional pulsation or half wave, substantially 60 electricaldegrees apart in phasesequence. Windings 281 to 2I2 of each oftransformers I98 to 283 are so connected with the out-going conductorsI88 to I9I and the return conductors I92 to I91 inclusive, that the sixdifferent wave trains or waves -of uni-directional pulsationsareselectively segregated and return over different return conductors.This is accomplished in precisely the same manner as the selectivesegregation process of Figure 1. It will thus be understood, that whileeach out-going conductor I88 to I9I and each.

return conductor I82 to I91 carry a plurality of unidirectionalpulsations of different phase sequence, nevertheless any one out-goingconducone return conductor represents only a single closed circuit. Thusthe uni-directional pulsations derived from secondary of my'invention,

The closed circuit of-winding.

282 and return conductor I98. The closed circuit of winding I84 oftransformer I1I' includes out-going conductor I88, winding 2 oftransformer 288 and return conductor I94. The closed circuit of windingI85 of transformer I includes out-going conductor I88, winding 2I2 oftransformer- 28I and return conductor I95. It will thus be seen that theuni-directional pulsations traveling out over out-going conductor I88are selectively segregated and return over return conductors I92, I93,I94, I95, I98 and I91. The closed circuit paths of windings I88 to I85of transformers I12 to I18 may be traced out in a'similar manner.

By virtue of the fact that there is a separate closed circuit for eachphase of uni-directional pulsations, it is possible to derive eithersingle or polyphase alternating current or pulsating inidirectionalcurrent anywhere along the transmission line through a step-downtransformer as described in connection with Figure 1 of the drawings. Athree phase take-off is indicated generally at 2I3 and a three wiredirect current take-oil. is indicated generally at 214.

and selective segregation and return of phase or polyphase alternatingcurrent or full or low voltage uni-directional. current which has beenobtained through static transforming means. It is of course to beunderstood that the drawings are diagrammatic only. ,For example, itwill be appreciated by those skilled in the art that separate iron coresshould be employed for each pair of secondary windings at thetransmitting end of the system and also for each pair of primarywindings at the receiving end or at the power take-oi! points of thesystem.

While I have shown particular embodiments it will, of course, beunderstood that I do not wish many modifications may be made, and Itherefore contemplate by the appended claims to cover all suchmodifications as fall within the true spirit and scope of my invention,

' I claim as my invention:

1. A power transmission system comprising a source of polyphasealternating current, full wave rectification means connected thereto forconverting the polyphase alternating current derived from said sourceinto polyphase pulsating uni-directional current, a plurality ofconducting paths forming a transmission line connected to said means,and a load circuit connected to said transmission line, said connectionsbeing such as to segregate the pulsations of diflerent time seto belimited thereto since.

' phase pulsating quences traveling out over each outgoing path of saidtransmission line and to return them over a plurality of differentconducting paths of said transmission line.

2. A power transmission system comprising a source of polyphasealternating current, full wave rectification means connected thereto forconverting the polyphase alternating current derived from said sourceinto polyphase pulsating unidirectional current, a plurality ofinterconnected closed circuits forming a transmission line connected tosaid means, and a load connected to said circuits, said circuits havingimpressed thereon uni-directional pulsations of different time sequence,no two pulsations of different time sequence being common to any onecomplete closed circuit.

3. A power transmission system comprising a source of polyphasealternating current, full Wave rectification means connected thereto forconverting the polyphase alternating current derived from said sourceinto polyphase pulsating uni-directional current, a plurality ofconducting paths for carrying said polyphase pulsating unidirectionalcurrent in one direction and a plurality of conducting paths forcarrying said polyuni-directional current in the opposite direction,said conducting paths forming a transmission line, and means forselectively segregating uni-directional pulsations of difierent phase onone of said first conducting paths and causing them to return overdiiferent second conducting paths.

A power transmission system comprising a source of polyphase alternatingcurrent, a plurality of electron discharge rectifiers each having aplurality of anodes and a cathode, a transmission line having aplurality of pairs of conductors, each of said pairs of conductorsincluding an outgoing conductor for carrying uni-d1- rectional currentin one direction and a return conductor for carrying uni-directionalcurrent in the opposite direction, the transmission ends of saidoutgoing conductors being each connected to a cathode of one of saidrectifiers, respectively, the anodes of said rectifiers being connectedto said source through means arranged to impress polyphaseuni-directional pulsating current on each of said outgoing conductors,means at the receiving end of said transmission line for selectivelysegregating uni-directional pulsations of difierent phase arriving atthe receiving end of each of said outgoing conductors and causing saidpulsations of different phase to return over different returnconductors, said return conductors being connected to said source in amanner to provide a plurality of closed paths with saidoutgoingconductors, any one outgoing conductor taken with any one returnconductor providing a single and only a single closed circuit.

5. A power transmission system comprising a source of polyphasealternating current, full wave rectification means connected thereto forconverting the polyphase alternating current derived from said sourceinto polyphase pulsating uni-directional current, a plurality ofconducting paths including outgoing conductors and return conductorsforming a transmission line connected to said means, and means connectedto said transmission line at the point remote from said first means forselectively segregating pulsations of difierent phase and causing themto return over different return conductors.

A power transmission system comprising'a source of polyphase alternatingcurrent, full wave rectification means connected thereto for convertingthe polyphase alternating current derived from said source intopolyphase pulsating uni-directi0nal current, a plurality of conductingpaths including outgoing conductors and return conductors forming atransmission line connected to said means, means connected to saidtransmission line at a point remote from said first means forselectively segregating pulsations of different phase and causing themto return over different return conductors, a local distributionnetwork, and means for inductively coupling said local distributionnetwork to said transmission line.

7. A power transmission system comprising a source of polyphasealternating current, full wave rectification means connected thereto forconverting the polyphase pulsating uni-directional current, a pluralityof conducting paths including outgoing conductors and return conductorsforming a transmission line connected to said source of polyphasealternating current, full wave rectification means connected thereto forconverting the polyphase alternating current derived from said sourceinto polyphase pulsating uni-directional current, a plurality ofconducting paths including outgoing conductors and return conductorsforming a transmission line connected to said means, means connected tosaid transmission line at a point remote from said first means forselectively segregating pulsations of diiferent phase and causing themto return over different return conductors, a local distributionnetwork, and static means for connecting said network to saidtransmission line in such a manner that alternating current power istransmitted over said local distribution network of the same frequencyas said source.

9. A power transmission system comprising a source of polyphasealternating current, full wave rectification means connected thereto forconverting the polyphase alternating current derived from said sourceinto polyphase pulsating uni-directional current, a plurality ofconducting paths including outgoing conductors and re turn conductorsforming a transmission line connected to. said means, means connected tosaid transmission line at a point remote from said first means forselectively segregating pulsations of different phase and causing themto return over diiferent return conductors, a local distributionnetwork, and static means for connecting said network to saidtransmission line in such a manner that alternating current power of adifierent number of phases but of the same frequency as said source istransmitted over said local distribution network.

10. The method of transmitting polyphase pulsating uni-directionalcurrent over a multiconductor transmission line which includestransmitting electric energy over one of said conductors in the form ofa plurality of half waves of different time phase with respect to eachother, selectively segregating half waves of difierent time phase andreturning them over different conductors of said transmission line;

11. A power transmission system connecting a principal distributionnetwork to a principal polyphase supply main, a group of statictransnected to said supply main, and a transmission line including aplurality of outgoing conductors anda plurality of return conductorsconnecting said groups of transformers together, said connections beingsuch that a plurality of closed circuits areformed and so arranged thatany one outgoing conductor and any one return conductor are common toonly a single closed path.

12. A power transmission system comprising a source of two phasealternating current, full wave rectification means connected thereto forconverting the two phase alternating current derived from said sourceinto pulsating uni-directional current in the form of wave trains eachtrain having four half waves of the same potential but out of phase 90with respect to'each other, a plurality of conductingpaths includingfour outgoing conductors and' four return conductors forming atransmission line connected to said means, a load circuit connected tosaid transmission line at a point remote from said first means forselectively seggregating the half waves of different phase and causingthem to return over different return conductors, and means connected tosaid load circuit for supply,- ing three phase power to a distributionnetwork. 13. A' power transmission system comprising a source ofpolyphase alternating current, a plurality of electron dischargerectifiers each having a plurality of anodes and a cathode, atransmission line having a plurality of pairs of conductors, each ofsaid pairs of conductors including an outgoing conductor for carryingunidirectional current in one direction and a return conductor forcarrying uni-directional current in the opposite direction, thetransmission ends of said outgoing conductors being each connected to acathode of one of said rectifiers, respectively, the anodes of saidrectifiers being connected to said source through means arranged toimpress polyphase uni-directional pulsating current on each of saidoutgoing conductors, means at the receiving end of said transmissionline for selectively segregating uni-directional pulsations of difierentphase arriving at the receiving end oi.

each of said'outgoing conductors, a plurality of electron dischargerectiflers each having a plurality of anodes and a cathode disposed atthe receiving end said transmission line, the oathode of each of saidlast named rectifiers being connected to a return conductor and theanodes of said last named rectifiers being connected to said segregatingmeans in such a manner that pulsations of different phase traveling outover any one outgoing conductor return over different return conductors,said return conductors being connected to said source in a manner toprovide a plurality of closed paths w1th said outgoing conductors, anyone outgoing conductor ,taken' with any one return conductor providing asingle and only a single closed circuit.

14. A transmission system adapted for the transmission of polyphasepulsating uni-directional current over a multi-conductor transmissionline, comprising a first plurality of rectifiers connected to one pointof the transmission system with each rectifier having a plurality ofanodes and a cathode, a first polyphase alternating current systemconnected with said first plurality of rectifiers, a second plurality ofrectifiers connected to another point o1 the transmission system witheach rectifier having a plurality of anodes and a cathode, a secondpolyphase alternating current system connected withsaid second pluralityof rectifiers, a plurality oi. pairs of conductor's connecting saidfirst and said second pluralities of rectifiers, with each of said pairsof conductors consisting of an outgoing line connected to a cathode of arectifier of said first plurality of rectifiers and of a return lineconnected to a cathode of a rectifier of said secondplurality 0trectifiers, respectively, and means' in circuit association with saidfirst and said second pluralities of 'rectiflers to segregateuni-directional currentimpulses of diflering phase relation carried bysaid pairs of conductors so that pulsations of different phasetravelling over any one outgoing conductor return over a plurality ofreturn conductors whereby a selected outgoing conductor and a selectedreturn conductor form a single closed path for a selected impulse in acertain phase relation.

